<!DOCTYPE html>
<html lang="zh-cn">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>html和css知识归纳</title>
    <style>
        body{
            margin:0;
            padding:0;
        }
        .box{
            width:100%;
            height:1200px;
            background-color:pink;
        }
    </style>
</head>
<body>
    <div class="box">
        <h1></h1>
    </div>
</body>
</html>